1. Technical Field
The present invention relates to an improved design and method of manufacturing a vibration motor, and more particularly, to an axial direction sliding-contact type brush apparatus of a flat type motor using in a silent call means for a mobile communications apparatus where the integrity of the electrical contact between the rotating commutator and the brush is improved by a damping effect of a resin applied in liquid form and then cured to serve to dampen vibrations a brush experiences.
2. Related Art
Due to recent developments in mobile communications technologies, mobile apparatuses are continuously made smaller and lighter. A compact flat vibrator motor is widely used as a silent call means in mobile communications.
A small flat vibrator motor has a structure having a flat rotor having a flat commutator attached thereto, the motor further having a flat magnet, an axial direction sliding-contact type brush and a flat brush base that are stacked with respect to a shaft in a small, flat cylindrical housing. In the flat motor having the above structure, the rotor is eccentric, for example, the rotor itself is formed to be eccentric and/or one or a plurality of armature coils are disposed on the flat rotor eccentric about the shaft. Thus, when the rotor is rotated as electric power is supplied to the armature coil via the commutator from the brush an unbalanced centrifugal force is generated by the eccentricity of the rotor and/or armature coil(s) and the vibrations are transferred to the housing through the shaft.
However, in the above flat vibrator motor, since the vibration that is generated by the rotation of the eccentric rotor is also transferred to the brush, the integrity of the electrical connection between the brush and the commutator is poor, resulting in the generation of sparks at a contact portion between the brush and the commutator due to the vibration of the motor. Furthermore, as the brush itself loses elasticity with age, the contact pressure of the brush with respect to the commutator decreases further hindering the integrity of the electrical connection between the commutator and the brush. In extreme cases, the motor stops and does not work at all.
Attempts to absorb the vibration transferred to the brush include attaching a damping member at a brush arm portion of the brush. However, in the case of a small and flat vibrator motor having the above structure, because the sizes of the motor and the brush are small, there is insufficient space to attach the damping member, making the attachment process very difficult. In particular, when a damping member is employed in a motor generating a strong vibration such as in a vibrator motor, since the damping member needs to be large in size and installed with a degree of accuracy, the installation process can become very complicated and expensive.